In the related art, a luminal re such as a down light has been commercialized which includes a light source having a semiconductor light emitting device such as an LED and is used, for example, in a state of being embedded and installed in a ceiling or the like.
Such a luminaire includes a lamp unit which has a light source and a turn-on circuit required for turning and driving the light source, a radiator for conducting and radiating heat generated by the lamp unit, and a terminal board which is provided in the radiator and to which a power source cable or the like for supplying a power source to the turn-on circuit is connected.
In recent years, in such a luminaire, a higher output of the light source such as an LED has been in progress. When increasing the electric power so as to promote the higher output of the light source, the temperature of the lamp unit itself rises along with the heating of the LED. The higher the electric power of the luminaire is, the higher the temperature of the lamp unit is, whereby the temperature of the radiator, to which heat generated by the lamp unit is conducted, also increases in proportion to the temperature of the lamp unit.
For this reason, to deal with the heat radiation caused by the higher output, a configuration is considered which increases an amount of heat conducted from the lamp unit to the radiator by increasing a contact surface between the lamp unit and the radiator, and raises heat radiation efficiency of the radiator. However, when increasing the contact area between the lamp unit and the radiator, as the temperature of the lamp unit becomes higher, the temperature of the radiator also rapidly rises.
Then, since heat from the radiator is conducted to a power source cable or the like required for lighting via the terminal board attached to the radiator, it is impossible to secure sufficient tolerance of the power source cable or the like depending on the temperature of the transmitted heat.
In general, the terminal board attached to the radiator, the power source cable connected to the terminal board or the like has the heat resistance of a predetermined given heat-resistant temperature, respectively. However, particularly, in a case where the temperature of heat transmitted from the radiator via the terminal board exceeds the heat-resistant temperature of the power source cable (for example, 70° C.), the tolerance of the power source cable important for the turn-on operation cannot be sufficiently secured, and as a consequence, a normal turn-on state cannot be maintained. For this reason, there is a need to protect the power source cable connected to the terminal board from heat.
However, in the luminal re of the related art, in a case where the temperature transmitted from the radiator to the power source cable or the like via the terminal board becomes higher than the heat-resistant temperature of the power source cable along with the higher output, there is a problem that it is difficult to secure the sufficient tolerance of the power source cable, that is, the power source cable connected to the terminal board cannot be sufficiently protected from heat.
Thus, the present embodiment has been made in view of the above problems, and an object thereof is to provide a luminaire which is able to protect the power source cable connected to the terminal board from heat by insulating the heat conducted from the radiator to the terminal board.